Diversified boundaries of the firm

We analyze diversification of boundaries of local firms in developing countries under the economic globalization. The globalization has an aspect of homogenization of the world economy, but also has another aspect of diversification through international economic activities. Focusing on boundary-level of the firm, this article shows that the diversification from a comparison with boundaries of foreign firms in developed countries is brought by a disadvantage of technology deficit and a home advantage as local firms.

Extensive boiling as a precipitation mechanism for precious and base metal ores, Bienaventurada Mine, Huancavelica, Perú

The Bienaventurada mine operates a polymetallic Ag-Pb-Zn (Cu, Au) vein system of the low sulphidation epithermal type. Fluid inclusions, FI, are abundant in quartz, sphalerite and adularia. FI petrography demonstrates typical primary growth zoning which occurs frequently in crystalline quartz, and defines the most common primary FI. These are usually very small, but several types of primary, P, and secondary, S, FI Assemblages (FIAs) comprising FI of measurable size (3 to > 100 μm) can also be identified through careful petrographic work. The fluids are aqueous and undersaturated, and no evidence of CO2 was found; the degree of fill is usually high (~70-80 %) in the L-rich inclusions, but extremely low in V-rich inclusions. The measured microthermometric values are very consistent in the FIAs selected; they are for the most part roughly similar in the P and S assemblages: the median is typically ~258ºC for total homogenization temperatures, Th, and -1.5 ºC for ice melting temperatures, Tm (corresponding to 2.57 wt% NaCl eq). The widespread occurrence of L-rich and V-rich FI in the same FIA and the consistent Th values point to an extensive boiling system along the vein. In these conditions, Th equals T of trapping, and the ores are assumed to have been precipitated from an aqueous low salinity boiling fluid, of likely meteoric origin, at some 250-280º C, under ~500 m hydrostatic head.

Freeform Fresnel RXI-RR Köhler design with spectrum-splitting for photovoltaics

The development of a novel optical design for the high concentration photovoltaics (HPCV) nonimaging concentrator (>500x) that utilizes a built-in spectrum splitting concept is presented. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it. The POE and SOE perform Köhler integration to produce light homogenization on the receiver. The system uses a combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-PointContact (BPC) silicon cell for efficient spectral utilization, and an external confinement technique for recovering the 3J cell’s reflection. A design target of an “equivalent” cell efficiency ~46% is predicted using commercial 39% 3J and 26% Si cells. A projected CPV module efficiency of greater than 38% is achievable at a concentration level greater than 500X with a wide acceptance angle of ±1º. A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J cell with a peak efficiency of 36.9%

Free-form Fresnel RXI-RR Köhler design for high-concentration photovoltaics with spectrum-splitting

Development of a novel HCPV nonimaging concentrator with high concentration (>500x) and built-in spectrum splitting concept is presented. It uses the combination of a commercial concentration GaInP/GaInAs/Ge 3J cell and a concentration Back-Point-Contact (BPC) silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell's reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free-form RXI-type concentrator with a band-pass filter embedded in it - Both the POE and SOE performing Köhler integration to produce light homogenization on the receiver. The band-pass filter transmits the IR photons in the 900-1200 nm band to the silicon cell. A design target of an "equivalent" cell efficiency ~46% is predicted using commercial 39% 3J and 26% Si cells. A projected CPV module efficiency of greater than 38% is achievable at a concentration level larger than 500X with a wide acceptance angle of ±1°. A first proof-of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ~100x and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J cell with a peak efficiency of 36.9%.

Ultra-High Efficiency, High-Concentration PV System Based On Spectral Division Between GaInP/GaInAs/Ge And BPC Silicon Cells

A novel HCPV nonimaging concentrator concept with high concentration (>500×) is presented. It uses the combination of a commercial concentration GaInP∕GaInAs∕Ge 3J cell and a concentration Back‐Point‐Contact (BPC) concentration silicon cell for efficient spectral utilization, and external confinement techniques for recovering the 3J cell′s reflection. The primary optical element (POE) is a flat Fresnel lens and the secondary optical element (SOE) is a free‐form RXI‐type concentrator with a band‐pass filter embedded it, both POE and SOE performing Köhler integration to produce light homogenization. The band‐pass filter sends the IR photons in the 900–1200 nm band to the silicon cell. Computer simulations predict that four‐terminal terminal designs could achieve ∼46% added cell efficiencies using commercial 39% 3J and 26% Si cells. A first proof‐of concept receiver prototype has been manufactured using a simpler optical architecture (with a lower concentration, ∼ 100× and lower simulated added efficiency), and experimental measurements have shown up to 39.8% 4J receiver efficiency using a 3J with peak efficiency of 36.9%

Advances in the Simultaneous Multiple Surface optical design method for imaging and non-imaging applications

Classical imaging optics has been developed over centuries in many areas, such as its paraxial imaging theory and practical design methods like multi-parametric optimization techniques. Although these imaging optical design methods can provide elegant solutions to many traditional optical problems, there are more and more new design problems, like solar concentrator, illumination system, ultra-compact camera, etc., that require maximum energy transfer efficiency, or ultra-compact optical structure. These problems do not have simple solutions from classical imaging design methods, because not only paraxial rays, but also non-paraxial rays should be well considered in the design process. Non-imaging optics is a newly developed optical discipline, which does not aim to form images, but to maximize energy transfer efficiency. One important concept developed from non-imaging optics is the “edge-ray principle”, which states that the energy flow contained in a bundle of rays will be transferred to the target, if all its edge rays are transferred to the target. Based on that concept, many CPC solar concentrators have been developed with efficiency close to the thermodynamic limit. When more than one bundle of edge-rays needs to be considered in the design, one way to obtain solutions is to use SMS method. SMS stands for Simultaneous Multiple Surface, which means several optical surfaces are constructed simultaneously. The SMS method was developed as a design method in Non-imaging optics during the 90s. The method can be considered as an extension to the Cartesian Oval calculation. In the traditional Cartesian Oval calculation, one optical surface is built to transform an input wave-front to an out-put wave-front. The SMS method however, is dedicated to solve more than 1 wave-fronts transformation problem. In the beginning, only 2 input wave-fronts and 2 output wave-fronts transformation problem was considered in the SMS design process for rotational optical systems or free-form optical systems. Usually “SMS 2D” method stands for the SMS procedure developed for rotational optical system, and “SMS 3D” method for the procedure for free-form optical system. Although the SMS method was originally employed in non-imaging optical system designs, it has been found during this thesis that with the improved capability to design more surfaces and control more input and output wave-fronts, the SMS method can also be applied to imaging system designs and possesses great advantage over traditional design methods. In this thesis, one of the main goals to achieve is to further develop the existing SMS-2D method to design with more surfaces and improve the stability of the SMS-2D and SMS-3D algorithms, so that further optimization process can be combined with SMS algorithms. The benefits of SMS plus optimization strategy over traditional optimization strategy will be explained in details for both rotational and free-form imaging optical system designs. Another main goal is to develop novel design concepts and methods suitable for challenging non-imaging applications, e.g. solar concentrator and solar tracker. This thesis comprises 9 chapters and can be grouped into two parts: the first part (chapter 2-5) contains research works in the imaging field, and the second part (chapter 6-8) contains works in the non-imaging field. In the first chapter, an introduction to basic imaging and non-imaging design concepts and theories is given. Chapter 2 presents a basic SMS-2D imaging design procedure using meridian rays. In this chapter, we will set the imaging design problem from the SMS point of view, and try to solve the problem numerically. The stability of this SMS-2D design procedure will also be discussed. The design concepts and procedures developed in this chapter lay the path for further improvement. Chapter 3 presents two improved SMS 3 surfaces’ design procedures using meridian rays (SMS-3M) and skew rays (SMS-1M2S) respectively. The major improvement has been made to the central segments selections, so that the whole SMS procedures become more stable compared to procedures described in Chapter 2. Since these two algorithms represent two types of phase space sampling, their image forming capabilities are compared in a simple objective design. Chapter 4 deals with an ultra-compact SWIR camera design with the SMS-3M method. The difficulties in this wide band camera design is how to maintain high image quality meanwhile reduce the overall system length. This interesting camera design provides a playground for the classical design method and SMS design methods. We will show designs and optical performance from both classical design method and the SMS design method. Tolerance study is also given as the end of the chapter. Chapter 5 develops a two-stage SMS-3D based optimization strategy for a 2 freeform mirrors imaging system. In the first optimization phase, the SMS-3D method is integrated into the optimization process to construct the two mirrors in an accurate way, drastically reducing the unknown parameters to only few system configuration parameters. In the second optimization phase, previous optimized mirrors are parameterized into Qbfs type polynomials and set up in code V. Code V optimization results demonstrates the effectiveness of this design strategy in this 2-mirror system design. Chapter 6 shows an etendue-squeezing condenser optics, which were prepared for the 2010 IODC illumination contest. This interesting design employs many non-imaging techniques such as the SMS method, etendue-squeezing tessellation, and groove surface design. This device has theoretical efficiency limit as high as 91.9%. Chapter 7 presents a freeform mirror-type solar concentrator with uniform irradiance on the solar cell. Traditional parabolic mirror concentrator has many drawbacks like hot-pot irradiance on the center of the cell, insufficient use of active cell area due to its rotational irradiance pattern and small acceptance angle. In order to conquer these limitations, a novel irradiance homogenization concept is developed, which lead to a free-form mirror design. Simulation results show that the free-form mirror reflector has rectangular irradiance pattern, uniform irradiance distribution and large acceptance angle, which confirm the viability of the design concept. Chapter 8 presents a novel beam-steering array optics design strategy. The goal of the design is to track large angle parallel rays by only moving optical arrays laterally, and convert it to small angle parallel output rays. The design concept is developed as an extended SMS method. Potential applications of this beam-steering device are: skylights to provide steerable natural illumination, building integrated CPV systems, and steerable LED illumination. Conclusion and future lines of work are given in Chapter 9. Resumen La óptica de formación de imagen clásica se ha ido desarrollando durante siglos, dando lugar tanto a la teoría de óptica paraxial y los métodos de diseño prácticos como a técnicas de optimización multiparamétricas. Aunque estos métodos de diseño óptico para formación de imagen puede aportar soluciones elegantes a muchos problemas convencionales, siguen apareciendo nuevos problemas de diseño óptico, concentradores solares, sistemas de iluminación, cámaras ultracompactas, etc. que requieren máxima transferencia de energía o dimensiones ultracompactas. Este tipo de problemas no se pueden resolver fácilmente con métodos clásicos de diseño porque durante el proceso de diseño no solamente se deben considerar los rayos paraxiales sino también los rayos no paraxiales. La óptica anidólica o no formadora de imagen es una disciplina que ha evolucionado en gran medida recientemente. Su objetivo no es formar imagen, es maximazar la eficiencia de transferencia de energía. Un concepto importante de la óptica anidólica son los “rayos marginales”, que se pueden utilizar para el diseño de sistemas ya que si todos los rayos marginales llegan a nuestra área del receptor, todos los rayos interiores también llegarán al receptor. Haciendo uso de este principio, se han diseñado muchos concentradores solares que funcionan cerca del límite teórico que marca la termodinámica. Cuando consideramos más de un haz de rayos marginales en nuestro diseño, una posible solución es usar el método SMS (Simultaneous Multiple Surface), el cuál diseña simultáneamente varias superficies ópticas. El SMS nació como un método de diseño para óptica anidólica durante los años 90. El método puede ser considerado como una extensión del cálculo del óvalo cartesiano. En el método del óvalo cartesiano convencional, se calcula una superficie para transformar un frente de onda entrante a otro frente de onda saliente. El método SMS permite transformar varios frentes de onda de entrada en frentes de onda de salida. Inicialmente, sólo era posible transformar dos frentes de onda con dos superficies con simetría de rotación y sin simetría de rotación, pero esta limitación ha sido superada recientemente. Nos referimos a “SMS 2D” como el método orientado a construir superficies con simetría de rotación y llamamos “SMS 3D” al método para construir superficies sin simetría de rotación o free-form. Aunque el método originalmente fue aplicado en el diseño de sistemas anidólicos, se ha observado que gracias a su capacidad para diseñar más superficies y controlar más frentes de onda de entrada y de salida, el SMS también es posible aplicarlo a sistemas de formación de imagen proporcionando una gran ventaja sobre los métodos de diseño tradicionales. Uno de los principales objetivos de la presente tesis es extender el método SMS-2D para permitir el diseño de sistemas con mayor número de superficies y mejorar la estabilidad de los algoritmos del SMS-2D y SMS-3D, haciendo posible combinar la optimización con los algoritmos. Los beneficios de combinar SMS y optimización comparado con el proceso de optimización tradicional se explican en detalle para sistemas con simetría de rotación y sin simetría de rotación. Otro objetivo importante de la tesis es el desarrollo de nuevos conceptos de diseño y nuevos métodos en el área de la concentración solar fotovoltaica. La tesis está estructurada en 9 capítulos que están agrupados en dos partes: la primera de ellas (capítulos 2-5) se centra en la óptica formadora de imagen mientras que en la segunda parte (capítulos 6-8) se presenta el trabajo del área de la óptica anidólica. El primer capítulo consta de una breve introducción de los conceptos básicos de la óptica anidólica y la óptica en formación de imagen. El capítulo 2 describe un proceso de diseño SMS-2D sencillo basado en los rayos meridianos. En este capítulo se presenta el problema de diseñar un sistema formador de imagen desde el punto de vista del SMS y se intenta obtener una solución de manera numérica. La estabilidad de este proceso se analiza con detalle. Los conceptos de diseño y los algoritmos desarrollados en este capítulo sientan la base sobre la cual se realizarán mejoras. El capítulo 3 presenta dos procedimientos para el diseño de un sistema con 3 superficies SMS, el primero basado en rayos meridianos (SMS-3M) y el segundo basado en rayos oblicuos (SMS-1M2S). La mejora más destacable recae en la selección de los segmentos centrales, que hacen más estable todo el proceso de diseño comparado con el presentado en el capítulo 2. Estos dos algoritmos representan dos tipos de muestreo del espacio de fases, su capacidad para formar imagen se compara diseñando un objetivo simple con cada uno de ellos. En el capítulo 4 se presenta un diseño ultra-compacto de una cámara SWIR diseñada usando el método SMS-3M. La dificultad del diseño de esta cámara de espectro ancho radica en mantener una alta calidad de imagen y al mismo tiempo reducir drásticamente sus dimensiones. Esta cámara es muy interesante para comparar el método de diseño clásico y el método de SMS. En este capítulo se presentan ambos diseños y se analizan sus características ópticas. En el capítulo 5 se describe la estrategia de optimización basada en el método SMS-3D. El método SMS-3D calcula las superficies ópticas de manera precisa, dejando sólo unos pocos parámetros libres para decidir la configuración del sistema. Modificando el valor de estos parámetros se genera cada vez mediante SMS-3D un sistema completo diferente. La optimización se lleva a cabo variando los mencionados parámetros y analizando el sistema generado. Los resultados muestran que esta estrategia de diseño es muy eficaz y eficiente para un sistema formado por dos espejos. En el capítulo 6 se describe un sistema de compresión de la Etendue, que fue presentado en el concurso de iluminación del IODC en 2010. Este interesante diseño hace uso de técnicas propias de la óptica anidólica, como el método SMS, el teselado de las lentes y el diseño mediante grooves. Este dispositivo tiene un límite teórica en la eficiencia del 91.9%. El capítulo 7 presenta un concentrador solar basado en un espejo free-form con irradiancia uniforme sobre la célula. Los concentradores parabólicos tienen numerosas desventajas como los puntos calientes en la zona central de la célula, uso no eficiente del área de la célula al ser ésta cuadrada y además tienen ángulos de aceptancia de reducido. Para poder superar estas limitaciones se propone un novedoso concepto de homogeneización de la irrandancia que se materializa en un diseño con espejo free-form. El análisis mediante simulación demuestra que la irradiancia es homogénea en una región rectangular y con mayor ángulo de aceptancia, lo que confirma la viabilidad del concepto de diseño. En el capítulo 8 se presenta un novedoso concepto para el diseño de sistemas afocales dinámicos. El objetivo del diseño es realizar un sistema cuyo haz de rayos de entrada pueda llegar con ángulos entre ±45º mientras que el haz de rayos a la salida sea siempre perpendicular al sistema, variando únicamente la posición de los elementos ópticos lateralmente. Las aplicaciones potenciales de este dispositivo son varias: tragaluces que proporcionan iluminación natural, sistemas de concentración fotovoltaica integrados en los edificios o iluminación direccionable con LEDs. Finalmente, el último capítulo contiene las conclusiones y las líneas de investigación futura.

Neighborhood-corrected interface discontinuity factors for multi-group pin-by-pin diffusion calculations for LWR

Performing three-dimensional pin-by-pin full core calculations based on an improved solution of the multi-group diffusion equation is an affordable option nowadays to compute accurate local safety parameters for light water reactors. Since a transport approximation is solved, appropriate correction factors, such as interface discontinuity factors, are required to nearly reproduce the fully heterogeneous transport solution. Calculating exact pin-by-pin discontinuity factors requires the knowledge of the heterogeneous neutron flux distribution, which depends on the boundary conditions of the pin-cell as well as the local variables along the nuclear reactor operation. As a consequence, it is impractical to compute them for each possible configuration; however, inaccurate correction factors are one major source of error in core analysis when using multi-group diffusion theory. An alternative to generate accurate pin-by-pin interface discontinuity factors is to build a functional-fitting that allows incorporating the environment dependence in the computed values. This paper suggests a methodology to consider the neighborhood effect based on the Analytic Coarse-Mesh Finite Difference method for the multi-group diffusion equation. It has been applied to both definitions of interface discontinuity factors, the one based on the Generalized Equivalence Theory and the one based on Black-Box Homogenization, and for different few energy groups structures. Conclusions are drawn over the optimal functional-fitting and demonstrative results are obtained with the multi-group pin-by-pin diffusion code COBAYA3 for representative PWR configurations.

Engineering metal precipitate size distributions to enhance gettering in multicrystalline silicon

The extraction of metal impurities during phosphorus diffusion gettering (PDG) is one of the crucial process steps when fabricating high-efficiency solar cells using low-cost, lower-purity silicon wafers. In this work, we show that for a given metal concentration, the size and density of metal silicide precipitates strongly influences the gettering efficacy. Different precipitate size distributions can be already found in silicon wafers grown by different techniques. In our experiment, however, the as-grown distribution of precipitated metals in multicrystalline Si sister wafers is engineered through different annealing treatments in order to control for the concentration and distribution of other defects. A high density of small precipitates is formed during a homogenization step, and a lower density of larger precipitates is formed during extended annealing at 740º C. After PDG, homogenized samples show a decreased interstitial iron concentration compared to as-grown and ripened samples, in agreement with simulations.

Divergence of the IGS rDNA in Fusarium proliferatum and Fusarium globosum reveals two strain specific non-orthologous types

A phylogenic analysis of Fusarium proliferatum and closely related species was performed using the most variable part within the intergenic spacer of the nuclear ribosomal DNA (IGS) and compared with a previously reported phylogeny performed in the same group of samples with a partial region of the nuclear single copy gene encoding the elongation factor 1α (EF-1α). The phylogenies from both genomic sequences were not concordant and revealed the presence of two nonorthologous IGS types, named types I and II, in F. proliferatum and Fusarium globosum. Two specific PCR assays designed to amplify either IGS type I or type II revealed that only one IGS type was present in each individual in these two species. The presence of both IGS types at the species level indicates that homogenization has not been achieved yet. This might be retarded if panmictic sexual reproduction was affected by certain levels of clonal reproduction and/or by the diverse hosts that these species are able to colonize. This study indicates that taxonomic studies carried out with the IGS rDNA, which has been widely used in Fusarium, should be undertaken with caution.

Failure locus of polypropylene nonwoven fabrics under in-plane biaxial deformation

The failure locus, the characteristics of the stress–strain curve and the damage localization patterns were analyzed in a polypropylene nonwoven fabric under in-plane biaxial deformation. The analysis was carried out by means of a homogenization model developed within the context of the finite element method. It provides the constitutive response for a mesodomain of the fabric corresponding to the area associated to a finite element and takes into account the main deformation and damage mechanisms experimentally observed. It was found that the failure locus in the stress space was accurately predicted by the Von Mises criterion and failure took place by the localization of damage into a crack perpendicular to the main loading axis.

Natural ventilation in underground wine cellars

The main objective of this research is to promote passive thermal design techniques in the construction of wineries. Natural ventilation in underground cellars is analyzed, focusing on the entrance tunnel, the ventilation chimney and the cave. A monitoring system was designed in order to detect changes in the indoor conditions and outdoor air infiltration. Monitoring process was carried out during one year. Results show the influence of outside temperature, ventilation chimney and access tunnel on the conditions inside the underground cellar. During hot periods, natural ventilation has a negligible influence on the indoor ambience, despite the permanently open vents in the door and chimney. The tunnel and ventilation chimney work as a temperature regulator, dampening outside fluctuations. Forced ventilation is necessary when a high air exchange ratio is needed. During cold periods, there is greater instability as a result of increased natural ventilation. The temperature differences along the tunnel are reduced, reflecting a homogenization and mixing of the air. The ventilation flow is sufficient to modify the temperature and relative humidity of the cave. Forced ventilation is not necessary in this period. During the intermediate periods --autumn and spring-- occurs different behaviors based on time of day.

Freeform optics applications in photovoltaic concentration

Freeform surfaces are the key of the state-of-the-art nonimaging optics to solve the challenges in concentration photovoltaics. Different families (FK, XR, FRXI) will be presented, based on the SMS 3D design method and Köhler homogenization.

Freeform optics for photovoltaic concentration

Freeform surfaces are the key of the state-of-the-art nonimaging optics to solve the challenges in concentration photovoltaics. Different families (FK, XR, FRXI) will be presented, based on the SMS 3D design method and Köhler homogenization.

Modelo de gestión por proyectos para el desarrollo local (MGPDL) en el marco de la nueva gestión pública. Aplicación a los distritos y barrios de la ciudad de Madrid

Esta investigación presenta un modelo de gestión para el ámbito público local enmarcado en la Nueva Gestión Pública que aboga por una gestión más eficaz, eficiente y transparente, y que pone el acento en la consideración del administrado como cliente y en las capacidades gerenciales y de liderazgo de los directivos públicos por encima de la función burocrática clásica. Asumiendo el concepto de comunidad política, en el que los ciudadanos y los gobernantes son corresponsables de la concertación política y social, y se pone en valor el conocimiento de la sociedad civil para la toma de decisiones, este modelo se expresa a través de un plan de acción para el desarrollo local que incorpora la estrategia empresarial “gestión por proyectos”, entendidos éstos como todos los proyectos que recogen las necesidades e ideas de los afectados, y que de alguna manera contribuyen al cambio o ayudan a transformar la realidad para la mejora de la calidad de vida. La realidad objeto de estudio que inspira este modelo es el primer plan de inversiones llevado a cabo en los distritos madrileños de Villaverde y Usera. Las características propias de este plan fueron la voluntad y la habilidad de los poderes públicos para transformar una movilización social reivindicativa en un proceso de planificación como aprendizaje social, integrando a los ciudadanos en un innovador sistema de gestión de responsabilidad compartida. El resultado fue considerado un éxito, ya que se cumplió el objetivo de reequilibrio social y económico de ambos distritos con el conjunto de la ciudad de Madrid, gracias a las infraestructuras y equipamientos construidos, y a los programas sociales implementados. De hecho, al concluir el plan, los problemas que originaron la movilización social apenas tenían relevancia: droga (5%), falta de equipamientos (3%) y baja calidad de vida (5%). A raíz del aprendizaje de esta experiencia desarrollada durante el período 1998‐ 2003, se construyó una metodología de actuación que se ha materializado en los actuales Planes especiales de actuación en distritos y Planes de Barrio de la ciudad de Madrid. Las evaluaciones realizadas hasta ahora determinan que se está logrando una homogeneización territorial en la oferta municipal de bienes, servicios y equipamientos públicos, lo que contribuye a una mayor equidad económica y social, en definitiva, a una mejor calidad de vida. ABSTRACT This research presents a management model for the public sector local framed in the New Public Management that advocates a public management more effective, efficient and transparent, and that puts the accent on the consideration of the citizen as client and in managerial and leadership skills of public managers over the classic bureaucratic function. Embracing the concept of political community, in which citizens and governments are jointly responsible for the political and social dialogue, and highlights the knowledge of the civil society to the decision‐making, this model is expressed through an action plan for local development that incorporates the business strategy "management by projects', understood these as all the projects that reflected the needs and ideas of those affected, and that in some way contribute to the change or help to transform the reality for the improvement of the quality of life. The reality which is subject of study and inspires this model is the first investment plan carried out in the districts of Madrid Villaverde and Usera. The characteristics of this plan were the will and the ability of the public authorities to transform a social mobilization in a planning process as social learning, integrating to citizens in an innovative system of management of shared responsibility. The result was considered a success, since the target was met for social and economic balance of the two districts with the whole of the city of Madrid, thanks to the built infrastructure and equipment, and the social programs implemented. In fact, at the end of the plan, the problems that led to the social mobilization had little relevance: drugs (5 %), lack of equipment (3 %) and low quality of life (5 %). As a result of learning from this experience developed during the period 1998‐ 2003, was built a methodology of performance which has been materialized in the current plans for special action in districts and plans of neighborhood of the city of Madrid. The evaluations conducted until now determine that the plans are achieving a territorial homogenization in the municipal supply of goods, services and public facilities, which contributes to a better economic and social equity, ultimately, to a better quality of life.

Aplicación de la física estadística a los medios granulares

Esta tesis se centra en el estudio de medios granulares blandos y atascados mediante la aplicación de la física estadística. Esta aproximación se sitúa entre los tradicionales enfoques macro y micromecánicos: trata de establecer cuáles son las propiedades macroscópicas esperables de un sistema granular en base a un análisis de las propiedades de las partículas y las interacciones que se producen entre ellas y a una consideración de las restricciones macroscópicas del sistema. Para ello se utiliza la teoría estadística junto con algunos principios, conceptos y definiciones de la teoría de los medios continuos (campo de tensiones y deformaciones, energía potencial elástica, etc) y algunas técnicas de homogeneización. La interacción entre las partículas es analizada mediante las aportaciones de la teoría del contacto y de las fuerzas capilares (producidas por eventuales meniscos de líquido cuando el medio está húmedo). La idea básica de la mecánica estadística es que entre todas soluciones de un problema físico (como puede ser el ensamblaje en equilibrio estático de partículas de un medio granular) existe un conjunto que es compatible con el conocimiento macroscópico que tenemos del sistema (por ejemplo, su volumen, la tensión a la que está sometido, la energía potencial elástica que almacena, etc.). Este conjunto todavía contiene un número enorme de soluciones. Pues bien, si no hay ninguna información adicional es razonable pensar que no existe ningún motivo para que alguna de estas soluciones sea más probable que las demás. Entonces parece natural asignarles a todas ellas el mismo peso estadístico y construir una función matemática compatible. Actuando de este modo se obtiene cuál es la función de distribución más probable de algunas cantidades asociadas a las soluciones, para lo cual es muy importante asegurarse de que todas ellas son igualmente accesibles por el procedimiento de ensamblaje o protocolo. Este enfoque se desarrolló en sus orígenes para el estudio de los gases ideales pero se puede extender para sistemas no térmicos como los analizados en esta tesis. En este sentido el primer intento se produjo hace poco más de veinte años y es la colectividad de volumen. Desde entonces esta ha sido empleada y mejorada por muchos investigadores en todo el mundo, mientras que han surgido otras, como la de la energía o la del fuerza-momento (tensión multiplicada por volumen). Cada colectividad describe, en definitiva, conjuntos de soluciones caracterizados por diferentes restricciones macroscópicas, pero de todos ellos resultan distribuciones estadísticas de tipo Maxwell-Boltzmann y controladas por dichas restricciones. En base a estos trabajos previos, en esta tesis se ha adaptado el enfoque clásico de la física estadística para el caso de medios granulares blandos. Se ha propuesto un marco general para estudiar estas colectividades que se basa en la comparación de todas las posibles soluciones en un espacio matemático definido por las componentes del fuerza-momento y en unas funciones de densidad de estados. Este desarrollo teórico se complementa con resultados obtenidos mediante simulación de la compresión cíclica de sistemas granulares bidimensionales. Se utilizó para ello un método de dinámica molecular, MD (o DEM). Las simulaciones consideran una interacción mecánica elástica, lineal y amortiguada a la que se ha añadido, en algunos casos, la fuerza cohesiva producida por meniscos de agua. Se realizaron cálculos en serie y en paralelo. Los resultados no solo prueban que las funciones de distribución de las componentes de fuerza-momento del sistema sometido a un protocolo específico parecen ser universales, sino que también revelan que existen muchos aspectos computacionales que pueden determinar cuáles son las soluciones accesibles. This thesis focuses on the application of statistical mechanics for the study of static and jammed packings of soft granular media. Such approach lies between micro and macromechanics: it tries to establish what the expected macroscopic properties of a granular system are, by starting from a micromechanical analysis of the features of the particles, and the interactions between them, and by considering the macroscopic constraints of the system. To do that, statistics together with some principles, concepts and definitions of continuum mechanics (e.g. stress and strain fields, elastic potential energy, etc.) as well as some homogenization techniques are used. The interaction between the particles of a granular system is examined too and theories on contact and capillary forces (when the media are wet) are revisited. The basic idea of statistical mechanics is that among the solutions of a physical problem (e.g. the static arrangement of particles in mechanical equilibrium) there is a class that is compatible with our macroscopic knowledge of the system (volume, stress, elastic potential energy,...). This class still contains an enormous number of solutions. In the absence of further information there is not any a priori reason for favoring one of these more than any other. Hence we shall naturally construct the equilibrium function by assigning equal statistical weights to all the functions compatible with our requirements. This procedure leads to the most probable statistical distribution of some quantities, but it is necessary to guarantee that all the solutions are likely accessed. This approach was originally set up for the study of ideal gases, but it can be extended to non-thermal systems too. In this connection, the first attempt for granular systems was the volume ensemble, developed about 20 years ago. Since then, this model has been followed and improved upon by many researchers around the world, while other two approaches have also been set up: energy and force-moment (i.e. stress multiplied by volume) ensembles. Each ensemble is described by different macroscopic constraints but all of them result on a Maxwell-Boltzmann statistical distribution, which is precisely controlled by the respective constraints. According to this previous work, in this thesis the classical statistical mechanics approach is introduced and adapted to the case of soft granular media. A general framework, which includes these three ensembles and uses a force-moment phase space and a density of states function, is proposed. This theoretical development is complemented by molecular dynamics (or DEM) simulations of the cyclic compression of 2D granular systems. Simulations were carried out by considering spring-dashpot mechanical interactions and attractive capillary forces in some cases. They were run on single and parallel processors. Results not only prove that the statistical distributions of the force-moment components obtained with a specific protocol seem to be universal, but also that there are many computational issues that can determine what the attained packings or solutions are.